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canvas.n
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canvas(n) Tk Commands
_________________________________________________________________
NAME
canvas - Create and manipulate canvas widgets
SYNOPSIS
canvas _p_a_t_h_N_a_m_e ?_o_p_t_i_o_n_s?
STANDARD OPTIONS
background insertBorderWidth reliefxScrollCommand
borderWidth insertOffTime selectBackgroundyScrollCommand |
cursor insertOnTime selectBorderWidth |
insertBackground insertWidth selectForeground|
See the ``options'' manual entry for details on the standard
options.
WIDGET-SPECIFIC OPTIONS
Name: closeEnough
Class: CloseEnough
Command-Line Switch:-closeenough
Specifies a floating-point value indicating how close
the mouse cursor must be to an item before it is con-
sidered to be ``inside'' the item. Defaults to 1.0.
Name: confine |
Class: Confine |
Command-Line Switch:-confine |
||
Specifies a boolean value that indicates whether or not |
it should be allowable to set the canvas's view outside |
the region defined by the scrollRegion argument. |
Defaults to true, which means that the view will be |
constrained within the scroll region.
Name: height
Class: Height
Command-Line Switch:-height
Specifies a desired window height that the canvas
widget should request from its geometry manager. The
value may be specified in any of the forms described in
the COORDINATES section below.
Name: scrollIncrement
Class: ScrollIncrement
Command-Line Switch:-scrollincrement
Specifies a distance used as increment during scrol-
ling: when one of the arrow buttons on an associated
Tk 1
canvas(n) Tk Commands
scrollbar is pressed, the picture will shift by this
distance. The distance may be specified in any of the
forms described in the COORDINATES section below.
Name: scrollRegion
Class: ScrollRegion
Command-Line Switch:-scrollregion
Specifies a list with four coordinates describing the
left, top, right, and bottom coordinates of a rectangu-
lar region. This region is used for scrolling purposes
and is considered to be the boundary of the information
in the canvas. Each of the coordinates may be speci-
fied in any of the forms given in the COORDINATES sec-
tion below.
Name: width
Class: width
Command-Line Switch:-width
Specifies a desired window width that the canvas widget
should request from its geometry manager. The value
may be specified in any of the forms described in the
COORDINATES section below.
_________________________________________________________________
INTRODUCTION
The canvas command creates a new window (given by the _p_a_t_h_-
_N_a_m_e argument) and makes it into a canvas widget. Addi-
tional options, described above, may be specified on the
command line or in the option database to configure aspects
of the canvas such as its colors and 3-D relief. The canvas
command returns its _p_a_t_h_N_a_m_e argument. At the time this
command is invoked, there must not exist a window named
_p_a_t_h_N_a_m_e, but _p_a_t_h_N_a_m_e's parent must exist.
Canvas widgets implement structured graphics. A canvas
displays any number of _i_t_e_m_s, which may be things like rec-
tangles, circles, lines, and text. Items may be manipulated
(e.g. moved or re-colored) and commands may be associated
with items in much the same way that the bind command allows
commands to be bound to widgets. For example, a particular
command may be associated with the <Button-1> event so that
the command is invoked whenever button 1 is pressed with the
mouse cursor over an item. This means that items in a can-
vas can have behaviors defined by the Tcl scripts bound to
them.
DISPLAY LIST
Tk 2
canvas(n) Tk Commands
The items in a canvas are ordered for purposes of display,
with the first item in the display list being displayed
first, followed by the next item in the list, and so on.
Items later in the display list obscure those that are ear-
lier in the display list and are sometimes referred to as
being ``on top'' of earlier items. When a new item is
created it is placed at the end of the display list, on top
of everything else. Widget commands may be used to re-
arrange the order of the display list.
ITEM IDS AND TAGS
Items in a canvas widget may be named in either of two ways:
by id or by tag. Each item has a unique identifying number
which is assigned to that item when it is created. The id
of an item never changes and id numbers are never re-used
within the lifetime of a canvas widget.
Each item may also have any number of _t_a_g_s associated with
it. A tag is just a string of characters, and it may take
any form except that of an integer. For example, ``x123''
is OK but ``123'' isn't. The same tag may be associated
with many different items. This is commonly done to group
items in various interesting ways; for example, all
selected items might be given the tag ``selected''.
The tag all is implicitly associated with every item in the
canvas; it may be used to invoke operations on all the
items in the canvas.
The tag current is managed automatically by Tk; it applies
to the _c_u_r_r_e_n_t _i_t_e_m, which is the topmost item whose drawn
area covers the position of the mouse cursor. If the mouse
is not in the canvas widget or is not over an item, then no
item has the current tag.
When specifying items in canvas widget commands, if the
specifier is an integer then it is assumed to refer to the
single item with that id. If the specifier is not an
integer, then it is assumed to refer to all of the items in
the canvas that have a tag matching the specifier. The sym-
bol _t_a_g_O_r_I_d is used below to indicate that an argument
specifies either an id that selects a single item or a tag
that selects zero or more items. Some widget commands only
operate on a single item at a time; if _t_a_g_O_r_I_d is specified
in a way that names multiple items, then the normal behavior
is for the command to use the first (lowest) of these items
in the display list that is suitable for the command.
Exceptions are noted in the widget command descriptions
below.
Tk 3
canvas(n) Tk Commands
COORDINATES
All coordinates related to canvases are stored as floating-
point numbers. Coordinates and distances are specified in
screen units, which are floating-point numbers optionally
followed by one of several letters. If no letter is sup-
plied then the distance is in pixels. If the letter is m
then the distance is in millimeters on the screen; if it is
c then the distance is in centimeters; i means inches, and p
means printers points (1/72 inch). Larger y-coordinates
refer to points lower on the screen; larger x-coordinates
refer to points farther to the right.
TRANSFORMATIONS
Normally the origin of the canvas coordinate system is at
the upper-left corner of the window containing the canvas.
It is possible to adjust the origin of the canvas coordinate
system relative to the origin of the window using the xview
and yview widget commands; this is typically used for
scrolling. Canvases do not support scaling or rotation of
the canvas coordinate system relative to the window coordi-
nate system.
Indidividual items may be moved or scaled using widget com-
mands described below, but they may not be rotated.
INDICES
Text items support the notion of an _i_n_d_e_x for identifying
particular positions within the item. Indices are used for
commands such as inserting text, deleting a range of charac-
ters, and setting the insertion cursor position. An index
may be specified in any of a number of ways, and different
types of items may support different forms for specifying
indices. Text items support the following forms for an
index; if you define new types of text-like items, it would
be advisable to support as many of these forms as practical.
Note that it is possible to refer to the character just
after the last one in the text item; this is necessary for
such tasks as inserting new text at the end of the item.
_n_u_m_b_e_r A decimal number giving the position of the
desired character within the text item. 0 refers
to the first character, 1 to the next character,
and so on. A number less than 0 is treated as if
it were zero, and a number greater than the length
of the text item is treated as if it were equal to
the length of the text item.
end Refers to the character just after the last one in
the item (same as the number of characters in the
item).
Tk 4
canvas(n) Tk Commands
insert Refers to the character just before which the |
insertion cursor is drawn in this item.
sel.first Refers to the first selected character in the
item. If the selection isn't in this item then
this form is illegal.
sel.last Refers to the last selected character in the item.
If the selection isn't in this item then this form
is illegal.
@_x,_y Refers to the character at the point given by _x
and _y, where _x and _y are specified in the coordi-
nate system of the canvas. If _x and _y lie outside
the coordinates covered by the text item, then
they refer to the first or last character in the
line that is closest to the given point.
WIDGET COMMAND
The canvas command creates a new Tcl command whose name is
_p_a_t_h_N_a_m_e. This command may be used to invoke various opera-
tions on the widget. It has the following general form:
_p_a_t_h_N_a_m_e _o_p_t_i_o_n ?_a_r_g _a_r_g ...?
_O_p_t_i_o_n and the _a_r_gs determine the exact behavior of the com-
mand. The following widget commands are possible for canvas
widgets:
_p_a_t_h_N_a_m_e addtag _t_a_g _s_e_a_r_c_h_S_p_e_c ?_a_r_g _a_r_g ...?
For each item that meets the constraints specified by
_s_e_a_r_c_h_S_p_e_c and the _a_r_gs, add _t_a_g to the list of tags
associated with the item if it isn't already present on
that list. It is possible that no items will satisfy
the constraints given by _s_e_a_r_c_h_S_p_e_c _a_n_d _a_r_gs, in which
case the command has no effect. This command returns
an empty string as result. _S_e_a_r_c_h_S_p_e_c and _a_r_g's may
take any of the following forms:
above _t_a_g_O_r_I_d
Selects the item just after (above) the one given
by _t_a_g_O_r_I_d in the display list. If _t_a_g_O_r_I_d
denotes more than one item, then the last (top-
most) of these items in the display list is used.
all Selects all the items in the canvas.
below _t_a_g_O_r_I_d
Selects the item just before (below) the one given
by _t_a_g_O_r_I_d in the display list. If _t_a_g_O_r_I_d
denotes more than one item, then the first
(lowest) of these items in the display list is
Tk 5
canvas(n) Tk Commands
used.
closest _x _y ?_h_a_l_o? ?_s_t_a_r_t?
Selects the item closest to the point given by _x
and _y. If more than one item is at the same
closest distance (e.g. two items overlap the
point), then the top-most of these items (the last
one in the display list) is used. If _h_a_l_o is
specified, then it must be a non-negative value.
Any item closer than _h_a_l_o to the point is con-
sidered to overlap it. The _s_t_a_r_t argument may be
used to step circularly through all the closest
items. If _s_t_a_r_t is specified, it names an item
using a tag or id (if by tag, it selects the first
item in the display list with the given tag).
Instead of selecting the topmost closest item,
this form will select the topmost closest item
that is below _s_t_a_r_t in the display list; if no
such item exists, then the selection behaves as if
the _s_t_a_r_t argument had not been specified.
enclosed _x_1 _y_1 _x_2 _y_2
Selects all the items completely enclosed within
the rectangular region given by _x_1, _y_1, _x_2, and
_y_2. _X_1 must be no greater then _x_2 and _y_1 must be
no greater than _y_2.
overlapping _x_1 _y_1 _x_2 _y_2
Selects all the items that overlap or are enclosed
within the rectangular region given by _x_1, _y_1, _x_2,
and _y_2. _X_1 must be no greater then _x_2 and _y_1 must
be no greater than _y_2.
withtag _t_a_g_O_r_I_d
Selects all the items given by _t_a_g_O_r_I_d.
_p_a_t_h_N_a_m_e bbox _t_a_g_O_r_I_d ?_t_a_g_O_r_I_d _t_a_g_O_r_I_d ...?
Returns a list with four elements giving an approximate |
bounding box for all the items named by the _t_a_g_O_r_I_d |
arguments. The list has the form ``_x_1 _y_1 _x_2 _y_2'' such |
that the drawn areas of all the named elements are |
within the region bounded by _x_1 on the left, _x_2 on the |
right, _y_1 on the top, and _y_2 on the bottom. The return |
value may overestimate the actual bounding box by a few |
pixels. If no items match any of the _t_a_g_O_r_I_d arguments |
then an empty string is returned.
_p_a_t_h_N_a_m_e bind _t_a_g_O_r_I_d ?_s_e_q_u_e_n_c_e? ?_c_o_m_m_a_n_d?
This command associates _c_o_m_m_a_n_d with all the items
given by _t_a_g_O_r_I_d such that whenever the event sequence
given by _s_e_q_u_e_n_c_e occurs for one of the items the com-
mand will be invoked. This widget command is similar
Tk 6
canvas(n) Tk Commands
to the bind command except that it operates on items in
a canvas rather than entire widgets. See the bind
manual entry for complete details on the syntax of
_s_e_q_u_e_n_c_e and the substitutions performed on _c_o_m_m_a_n_d
before invoking it. If all arguments are specified
then a new binding is created, replacing any existing
binding for the same _s_e_q_u_e_n_c_e and _t_a_g_O_r_I_d (if the first
character of _c_o_m_m_a_n_d is ``+'' then _c_o_m_m_a_n_d augments an
existing binding rather than replacing it). In this
case the return value is an empty string. If _c_o_m_m_a_n_d
is omitted then the command returns the _c_o_m_m_a_n_d associ-
ated with _t_a_g_O_r_I_d and _s_e_q_u_e_n_c_e (an error occurs if
there is no such binding). If both _c_o_m_m_a_n_d and
_s_e_q_u_e_n_c_e are omitted then the command returns a list of
all the sequences for which bindings have been defined
for _t_a_g_O_r_I_d.
The only events for which bindings may be specified are
those related to the mouse and keyboard, such as Enter,
Leave, ButtonPress, Motion, and KeyPress. The handling
of events in canvases uses the current item defined in
ITEM IDS AND TAGS above. Enter and Leave events
trigger for an item when it becomes the current item or
ceases to be the current item; note that these events
are different than Enter and Leave events for windows.
Mouse-related events are directed to the current item,
if any. Keyboard-related events are directed to the
focus item, if any (see the focus widget command below
for more on this).
It is possible for multiple commands to be bound to a
single event sequence for a single object. This
occurs, for example, if one command is associated with
the item's id and another is associated with one of the
item's tags. When this occurs, the first matching
binding is used. A binding for the item's id has
highest priority, followed by the oldest tag for the
item and proceeding through all of the item's tags up
through the most-recently-added one. If a binding is
associated with the tag all, the binding will have
lower priority than all other bindings associated with
the item.
_p_a_t_h_N_a_m_e canvasx _s_c_r_e_e_n_x ?_g_r_i_d_s_p_a_c_i_n_g?
Given a screen x-coordinate _s_c_r_e_e_n_x this command
returns the canvas x-coordinate that is displayed at
that location. If _g_r_i_d_s_p_a_c_i_n_g is specified, then the
canvas coordinate is rounded to the nearest multiple of
_g_r_i_d_s_p_a_c_i_n_g units.
_p_a_t_h_N_a_m_e canvasy _s_c_r_e_e_n_y ?_g_r_i_d_s_p_a_c_i_n_g?
Given a screen y-coordinate _s_c_r_e_e_n_y this command
Tk 7
canvas(n) Tk Commands
returns the canvas y-coordinate that is displayed at
that location. If _g_r_i_d_s_p_a_c_i_n_g is specified, then the
canvas coordinate is rounded to the nearest multiple of
_g_r_i_d_s_p_a_c_i_n_g units.
_p_a_t_h_N_a_m_e configure ?_o_p_t_i_o_n? ?_v_a_l_u_e? ?_o_p_t_i_o_n _v_a_l_u_e ...?
Query or modify the configuration options of the
widget. If no _o_p_t_i_o_n is specified, returns a list
describing all of the available options for _p_a_t_h_N_a_m_e
(see Tk_ConfigureInfo for information on the format of
this list). If _o_p_t_i_o_n is specified with no _v_a_l_u_e, then
the command returns a list describing the one named
option (this list will be identical to the correspond-
ing sublist of the value returned if no _o_p_t_i_o_n is
specified). If one or more _o_p_t_i_o_n-_v_a_l_u_e pairs are
specified, then the command modifies the given widget
option(s) to have the given value(s); in this case the
command returns an empty string. _O_p_t_i_o_n may have any
of the values accepted by the canvas command.
_p_a_t_h_N_a_m_e coords _t_a_g_O_r_I_d ?_x_0 _y_0 ...?
Query or modify the coordinates that define an item. |
If no coordinates are specified, this command returns a |
list whose elements are the coordinates of the item |
named by _t_a_g_O_r_I_d. If coordinates are specified, then |
they replace the current coordinates for the named |
item. If _t_a_g_O_r_I_d refers to multiple items, then the |
first one in the display list is used.
_p_a_t_h_N_a_m_e create _t_y_p_e _x _y ?_x _y ...? ?_o_p_t_i_o_n _v_a_l_u_e ...?
Create a new item in _p_a_t_h_N_a_m_e of type _t_y_p_e. The exact
format of the arguments after type depends on type, but
usually they consist of the coordinates for one or more
points, followed by specifications for zero or more
item options. See the subsections on individual item
types below for more on the syntax of this command.
This command returns the id for the new item.
_p_a_t_h_N_a_m_e dchars _t_a_g_O_r_I_d _f_i_r_s_t ?_l_a_s_t?
For each item given by _t_a_g_O_r_I_d, delete the characters
in the range given by _f_i_r_s_t and _l_a_s_t, inclusive. If
some of the items given by _t_a_g_O_r_I_d don't support text
operations, then they are ignored. _F_i_r_s_t and _l_a_s_t are
indices of characters within the item(s) as described
in INDICES above. If _l_a_s_t is omitted, it defaults to
_f_i_r_s_t. This command returns an empty string.
_p_a_t_h_N_a_m_e delete ?_t_a_g_O_r_I_d _t_a_g_O_r_I_d ...?
Delete each of the items given by each _t_a_g_O_r_I_d, and
return an empty string. |
_p_a_t_h_N_a_m_e dtag _t_a_g_O_r_I_d ?tagToDelete?
Tk 8
canvas(n) Tk Commands
For each of the items given by _t_a_g_O_r_I_d, delete the tag
given by _t_a_g_T_o_D_e_l_e_t_e from the list of those associated
with the item. If an item doesn't have the tag _t_a_g_T_o_-
_D_e_l_e_t_e then the item is unaffected by the command. If
_t_a_g_T_o_D_e_l_e_t_e is omitted then it defaults to _t_a_g_O_r_I_d.
This command returns an empty string.
_p_a_t_h_N_a_m_e find _s_e_a_r_c_h_C_o_m_m_a_n_d ?_a_r_g _a_r_g ...?
This command returns a list consisting of all the items
that meet the constraints specified by _s_e_a_r_c_h_C_o_m_m_a_n_d
and _a_r_g's. _S_e_a_r_c_h_C_o_m_m_a_n_d and _a_r_g_s have any of the
forms accepted by the addtag command.
_p_a_t_h_N_a_m_e focus ?_t_a_g_O_r_I_d?
Set the keyboard focus for the canvas widget to the
item given by _t_a_g_O_r_I_d. If _t_a_g_O_r_I_d refers to several
items, then the focus is set to the first such item in
the display list that supports the insertion cursor.
If _t_a_g_O_r_I_d doesn't refer to any items, or if none of
them support the insertion cursor, then the focus isn't
changed. If _t_a_g_O_r_I_d is an empty string, then the focus
item is reset so that no item has the focus. If
_t_a_g_O_r_I_d is not specified then the command returns the
id for the item that currently has the focus, or an
empty string if no item has the focus.
Once the focus has been set to an item, the item will
display the insertion cursor and all keyboard events
will be directed to that item. The focus item within a
canvas and the focus window on the screen (set with the
focus command) are totally independent: a given item
doesn't actually have the input focus unless (a) its
canvas is the focus window and (b) the item is the
focus item within the canvas. In most cases it is
advisable to follow the focus widget command with the
focus command to set the focus window to the canvas (if
it wasn't there already).
_p_a_t_h_N_a_m_e gettags _t_a_g_O_r_I_d
Return a list whose elements are the tags associated
with the item given by _t_a_g_O_r_I_d. If _t_a_g_O_r_I_d refers to
more than one item, then the tags are returned from the
first such item in the display list. If _t_a_g_O_r_I_d
doesn't refer to any items, or if the item contains no
tags, then an empty string is returned.
_p_a_t_h_N_a_m_e icursor _t_a_g_O_r_I_d _i_n_d_e_x
Set the position of the insertion cursor for the |
item(s) given by _t_a_g_O_r_I_d to just before the character |
whose position is given by _i_n_d_e_x. If some or all of |
the items given by _t_a_g_O_r_I_d don't support an insertion |
cursor then this command has no effect on them. See |
Tk 9
canvas(n) Tk Commands
INDICES above for a description of the legal forms for |
_i_n_d_e_x. Note: the insertion cursor is only displayed |
in an item if that item currently has the keyboard |
focus (see the widget command focus, below), but the |
cursor position may be set even when the item doesn't |
have the focus. This command returns an empty string.
_p_a_t_h_N_a_m_e index _t_a_g_O_r_I_d _i_n_d_e_x
This command returns a decimal string giving the numer-
ical index within _t_a_g_O_r_I_d corresponding to _i_n_d_e_x.
_I_n_d_e_x gives a textual description of the desired posi-
tion as described in INDICES above. The return value
is guaranteed to lie between 0 and the number of char-
acters within the item, inclusive. If _t_a_g_O_r_I_d refers
to multiple items, then the index is processed in the
first of these items that supports indexing operations
(in display list order).
_p_a_t_h_N_a_m_e insert _t_a_g_O_r_I_d _b_e_f_o_r_e_T_h_i_s _s_t_r_i_n_g
For each of the items given by _t_a_g_O_r_I_d, if the item
supports text insertion then _s_t_r_i_n_g is inserted into
the item's text just before the character whose index
is _b_e_f_o_r_e_T_h_i_s. See INDICES above for information about
the forms allowed for _b_e_f_o_r_e_T_h_i_s. This command returns
an empty string.
_p_a_t_h_N_a_m_e itemconfigure _t_a_g_O_r_I_d ?_o_p_t_i_o_n? ?_v_a_l_u_e? ?_o_p_t_i_o_n _v_a_l_u_e
This command is similar to the configure widget command
except that it modifies item-specific options for the
items given by _t_a_g_O_r_I_d instead of modifying options for
the overall canvas widget. If no _o_p_t_i_o_n is specified,
returns a list describing all of the available options
for the first item given by _t_a_g_O_r_I_d (see
Tk_ConfigureInfo for information on the format of this
list). If _o_p_t_i_o_n is specified with no _v_a_l_u_e, then the
command returns a list describing the one named option
(this list will be identical to the corresponding sub-
list of the value returned if no _o_p_t_i_o_n is specified).
If one or more _o_p_t_i_o_n-_v_a_l_u_e pairs are specified, then
the command modifies the given widget option(s) to have
the given value(s) in each of the items given by
_t_a_g_O_r_I_d; in this case the command returns an empty
string. The _o_p_t_i_o_ns and _v_a_l_u_es are the same as those
permissible in the create widget command when the
item(s) were created; see the sections describing indi-
vidual item types below for details on the legal
options.
_p_a_t_h_N_a_m_e lower _t_a_g_O_r_I_d ?_b_e_l_o_w_T_h_i_s?
Move all of the items given by _t_a_g_O_r_I_d to a new posi-
tion in the display list just before the item given by
_b_e_l_o_w_T_h_i_s. If _t_a_g_O_r_I_d refers to more than one item
Tk 10
canvas(n) Tk Commands
then all are moved but the relative order of the moved
items will not be changed. _B_e_l_o_w_T_h_i_s is a tag or id;
if it refers to more than one item then the first
(lowest) of these items in the display list is used as
the destination location for the moved items. This
command returns an empty string.
_p_a_t_h_N_a_m_e move _t_a_g_O_r_I_d _x_A_m_o_u_n_t _y_A_m_o_u_n_t
Move each of the items given by _t_a_g_O_r_I_d in the canvas
coordinate space by adding _x_A_m_o_u_n_t to the x-coordinate
of each point associated with the item and _y_A_m_o_u_n_t to
the y-coordinate of each point associated with the
item. This command returns an empty string.
_p_a_t_h_N_a_m_e postscript ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?
Generate a Postscript representation for part or all of |
the canvas. If the -file option is specified then the |
Postscript is written to a file and an empty string is |
returned; otherwise the Postscript is returned as the |
result of the command. The Postscript is created in |
Encapsulated Postscript form using version 3.0 of the |
Document Structuring Conventions. The _o_p_t_i_o_n-_v_a_l_u_e |
argument pairs provide additional information to con- |
trol the generation of Postscript. The following |
options are supported: |
-colormap _v_a_r_N_a_m_e ||
_V_a_r_N_a_m_e must be the name of a global array vari- |
able that specifies a color mapping to use in the |
Postscript. Each element of _v_a_r_N_a_m_e must consist |
of Postscript code to set a particular color value |
(e.g. ``1.0 1.0 0.0 setrgbcolor''). When output- |
ting color information in the Postscript, Tk |
checks to see if there is an element of _v_a_r_N_a_m_e |
with the same name as the color. If so, Tk uses |
the value of the element as the Postscript command |
to set the color. If this option hasn't been |
specified, or if there isn't an entry in _v_a_r_N_a_m_e |
for a given color, then Tk uses the red, green, |
and blue intensities from the X color. |
-colormode _m_o_d_e ||
Specifies how to output color information. _M_o_d_e |
must be either color (for full color output), gray |
(convert all colors to their gray-scale |
equivalents) or mono (convert all colors to black |
or white). |
-file _f_i_l_e_N_a_m_e ||
Specifies the name of the file in which to write |
the Postscript. If this option isn't specified |
then the Postscript is returned as the result of |
Tk 11
canvas(n) Tk Commands
the command instead of being written to a file. |
-fontmap _v_a_r_N_a_m_e ||
_V_a_r_N_a_m_e must be the name of a global array vari- |
able that specifies a font mapping to use in the |
Postscript. Each element of _v_a_r_N_a_m_e must consist |
of a Tcl list with two elements, which are the |
name and point size of a Postscript font. When |
outputting Postscript commands for a particular |
font, Tk checks to see if _v_a_r_N_a_m_e contains an ele- |
ment with the same name as the font. If there is |
such an element, then the font information con- |
tained in that element is used in the Postscript. |
Otherwise Tk attempts to guess what Postscript |
font to use. Tk's guesses generally only work for |
well-known fonts such as Times and Helvetica and |
Courier, and only if the X font name does not omit |
any dashes up through the point size. For exam- |
ple, -*-Courier-Bold-R-Normal--*-120-* will work |
but *Courier-Bold-R-Normal*120* will not; Tk |
needs the dashes to parse the font name). |
-height _s_i_z_e ||
Specifies the height of the area of the canvas to |
print. Defaults to the height of the canvas win- |
dow. |
-pageanchor _a_n_c_h_o_r ||
Specifies which point of the printed area should |
be appear over the positioning point on the page |
(which is given by the -pagex and -pagey options). |
For example, -pageanchor n means that the top |
center of the printed area should be over the |
positioning point. Defaults to center. |
-pageheight _s_i_z_e ||
Specifies that the Postscript should be scaled in |
both x and y so that the printed area is _s_i_z_e high |
on the Postscript page. _S_i_z_e consists of a |
floating-point number followed by c for centime- |
ters, i for inches, m for millimeters, or p or |
nothing for printer's points (1/72 inch). |
Defaults to the height of the printed area on the |
screen. If both -pageheight and -pagewidth are |
specified then the scale factor from the later |
option is used (non-uniform scaling is not imple- |
mented). |
-pagewidth _s_i_z_e ||
Specifies that the Postscript should be scaled in |
both x and y so that the printed area is _s_i_z_e wide |
on the Postscript page. _S_i_z_e has the same form as |
Tk 12
canvas(n) Tk Commands
for -pageheight. Defaults to the width of the |
printed area on the screen. If both -pageheight |
and -pagewidth are specified then the scale factor |
from the later option is used (non-uniform scaling |
is not implemented). |
-pagex _p_o_s_i_t_i_o_n ||
_P_o_s_i_t_i_o_n gives the x-coordinate of the positioning |
point on the Postscript page, using any of the |
forms allowed for -pageheight. Used in conjunc- |
tion with the -pagey and -pageanchor options to |
determine where the printed area appears on the |
Postscript page. Defaults to the center of the |
page. |
-pagey _p_o_s_i_t_i_o_n ||
_P_o_s_i_t_i_o_n gives the y-coordinate of the positioning |
point on the Postscript page, using any of the |
forms allowed for -pageheight. Used in conjunc- |
tion with the -pagex and -pageanchor options to |
determine where the printed area appears on the |
Postscript page. Defaults to the center of the |
page. |
-rotate _b_o_o_l_e_a_n ||
_B_o_o_l_e_a_n specifies whether the printed area is to |
be rotated 90 degrees. In non-rotated output the |
x-axis of the printed area runs along the short |
dimension of the page (``portrait'' orientation); |
in rotated output the x-axis runs along the long |
dimension of the page (``landscape'' orientation). |
Defaults to non-rotated. |
-width _s_i_z_e ||
Specifies the width of the area of the canvas to |
print. Defaults to the width of the canvas win- |
dow. |
-x _p_o_s_i_t_i_o_n ||
Specifies the x-coordinate of the left edge of the |
area of the canvas that is to be printed, in can- |
vas coordinates, not window coordinates. Defaults |
to the coordinate of the left edge of the window. |
-y _p_o_s_i_t_i_o_n ||
Specifies the y-coordinate of the top edge of the |
area of the canvas that is to be printed, in can- |
vas coordinates, not window coordinates. Defaults |
to the coordinate of the top edge of the window. |
_p_a_t_h_N_a_m_e raise _t_a_g_O_r_I_d ?_a_b_o_v_e_T_h_i_s?
Move all of the items given by _t_a_g_O_r_I_d to a new
Tk 13
canvas(n) Tk Commands
position in the display list just after the item given
by _a_b_o_v_e_T_h_i_s. If _t_a_g_O_r_I_d refers to more than one item
then all are moved but the relative order of the moved
items will not be changed. _A_b_o_v_e_T_h_i_s is a tag or id;
if it refers to more than one item then the last (top-
most) of these items in the display list is used as the
destination location for the moved items. This command
returns an empty string.
_p_a_t_h_N_a_m_e scale _t_a_g_O_r_I_d _x_O_r_i_g_i_n _y_O_r_i_g_i_n _x_S_c_a_l_e _y_S_c_a_l_e
Rescale all of the items given by _t_a_g_O_r_I_d in canvas
coordinate space. _X_O_r_i_g_i_n and _y_O_r_i_g_i_n identify the
origin for the scaling operation and _x_S_c_a_l_e and _y_S_c_a_l_e
identify the scale factors for x- and y-coordinates,
respectively (a scale factor of 1.0 implies no change
to that coordinate). For each of the points defining
each item, the x-coordinate is adjusted to change the
distance from _x_O_r_i_g_i_n by a factor of _x_S_c_a_l_e. Simi-
larly, each y-coordinate is adjusted to change the dis-
tance from _y_O_r_i_g_i_n by a factor of _y_S_c_a_l_e. This command
returns an empty string.
_p_a_t_h_N_a_m_e scan _o_p_t_i_o_n _a_r_g_s
This command is used to implement scanning on canvases.
It has two forms, depending on _o_p_t_i_o_n:
_p_a_t_h_N_a_m_e scan mark _x _y
Records _x and _y and the canvas's current view;
used in conjunction with later scan dragto com-
mands. Typically this command is associated with
a mouse button press in the widget and _x and _y are
the coordinates of the mouse. It returns an empty
string.
_p_a_t_h_N_a_m_e scan dragto _x _y.
This command computes the difference between its _x
and _y arguments (which are typically mouse coordi-
nates) and the _x and _y arguments to the last scan
mark command for the widget. It then adjusts the
view by 10 times the difference in coordinates.
This command is typically associated with mouse
motion events in the widget, to produce the effect
of dragging the canvas at high speed through its
window. The return value is an empty string.
_p_a_t_h_N_a_m_e select _o_p_t_i_o_n ?_t_a_g_O_r_I_d _a_r_g?
Manipulates the selection in one of several ways,
depending on _o_p_t_i_o_n. The command may take any of the
forms described below. In all of the descriptions
below, _t_a_g_O_r_I_d must refer to an item that supports
indexing and selection; if it refers to multiple items
then the first of these that supports indexing and the
Tk 14
canvas(n) Tk Commands
selection is used. _I_n_d_e_x gives a textual description
of a position within _t_a_g_O_r_I_d, as described in INDICES
above.
_p_a_t_h_N_a_m_e select adjust _t_a_g_O_r_I_d _i_n_d_e_x
Locate the end of the selection in _t_a_g_O_r_I_d nearest
to the character given by _i_n_d_e_x, and adjust that
end of the selection to be at _i_n_d_e_x (i.e. includ-
ing but not going beyond _i_n_d_e_x). The other end of
the selection is made the anchor point for future
select to commands. If the selection isn't
currently in _t_a_g_O_r_I_d then this command behaves the
same as the select to widget command. Returns an
empty string.
_p_a_t_h_N_a_m_e select clear
Clear the selection if it is in this widget. If
the selection isn't in this widget then the com-
mand has no effect. Returns an empty string.
_p_a_t_h_N_a_m_e select from _t_a_g_O_r_I_d _i_n_d_e_x
Set the selection anchor point for the widget to
be just before the character given by _i_n_d_e_x in the
item given by _t_a_g_O_r_I_d. This command doesn't
change the selection; it just sets the fixed end
of the selection for future select to commands.
Returns an empty string.
_p_a_t_h_N_a_m_e select item
Returns the id of the selected item, if the selec-
tion is in an item in this canvas. If the selec-
tion is not in this canvas then an empty string is
returned.
_p_a_t_h_N_a_m_e select to _t_a_g_O_r_I_d _i_n_d_e_x
Set the selection to consist of those characters
of _t_a_g_O_r_I_d between the selection anchor point and
_i_n_d_e_x. The new selection will include the charac-
ter given by _i_n_d_e_x; it will include the character
given by the anchor point only if _i_n_d_e_x is greater
than or equal to the anchor point. The anchor
point is determined by the most recent select
adjust or select from command for this widget. If
the selection anchor point for the widget isn't
currently in _t_a_g_O_r_I_d, then it is set to the same
character given by _i_n_d_e_x. Returns an empty
string.
_p_a_t_h_N_a_m_e type _t_a_g_O_r_I_d
Returns the type of the item given by _t_a_g_O_r_I_d, such as
rectangle or text. If _t_a_g_O_r_I_d refers to more than one
item, then the type of the first item in the display
Tk 15
canvas(n) Tk Commands
list is returned. If _t_a_g_O_r_I_d doesn't refer to any
items at all then an empty string is returned.
_p_a_t_h_N_a_m_e xview _i_n_d_e_x
Change the view in the canvas so that the canvas posi-
tion given by _i_n_d_e_x appears at the left edge of the
window. This command is typically used by scrollbars
to scroll the canvas. _I_n_d_e_x counts in units of scroll
increments (the value of the scrollIncrement option):
a value of 0 corresponds to the left edge of the scroll
region (as defined by the scrollRegion option), a
value of 1 means one scroll unit to the right of this,
and so on. The return value is an empty string.
_p_a_t_h_N_a_m_e yview _i_n_d_e_x
Change the view in the canvas so that the canvas posi-
tion given by _i_n_d_e_x appears at the top edge of the win-
dow. This command is typically used by scrollbars to
scroll the canvas. _I_n_d_e_x counts in units of scroll
increments (the value of the scrollIncrement option):
a value of 0 corresponds to the top edge of the scroll
region (as defined by the scrollRegion option), a
value of 1 means one scroll unit below this, and so on.
The return value is an empty string.
OVERVIEW OF ITEM TYPES
The sections below describe the various types of items sup-
ported by canvas widgets. Each item type is characterized
by two things: first, the form of the create command used to
create instances of the type; and second, a set of confi-
guration options for items of that type, which may be used
in the create and itemconfigure widget commands. Most items
don't support indexing or selection or the commands related
to them, such as index and insert. Where items do support
these facilities, it is noted explicitly in the descriptions
below (at present, only text items provide this support).
ARC ITEMS
Items of type arc appear on the display as arc-shaped |
regions. An arc is a section of an oval delimited by two |
angles (specified by the -start and -extent options) and |
displayed in one of several ways (specified by the -style |
option). Arcs are created with widget commands of the fol- |
lowing form: |
_p_a_t_h_N_a_m_e create arc _x_1 _y_1 _x_2 _y_2 ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?|
The arguments _x_1, _y_1, _x_2, and _y_2 give the coordinates of two |
diagonally opposite corners of a rectangular region enclos- |
ing the oval that defines the arc. After the coordinates |
there may be any number of _o_p_t_i_o_n-_v_a_l_u_e pairs, each of which |
Tk 16
canvas(n) Tk Commands
sets one of the configuration options for the item. These |
same _o_p_t_i_o_n-_v_a_l_u_e pairs may be used in itemconfigure widget |
commands to change the item's configuration. The following |
options are supported for arcs: |
-extent _d_e_g_r_e_e_s ||
Specifies the size of the angular range occupied by the |
arc. The arc's range extends for _d_e_g_r_e_e_s degrees |
counter-clockwise from the starting angle given by the |
-start option. _D_e_g_r_e_e_s may be negative. |
-fill _c_o_l_o_r ||
Fill the region of the arc with _c_o_l_o_r. _C_o_l_o_r may have |
any of the forms accepted by Tk_GetColor. If _c_o_l_o_r is |
an empty string (the default), then then the arc will |
not be filled. |
-outline _c_o_l_o_r ||
_C_o_l_o_r specifies a color to use for drawing the arc's |
outline; it may have any of the forms accepted by |
Tk_GetColor. This option defaults to black. If the |
arc's style is arc then this option is ignored (the |
section of perimeter is filled using the -fill option). |
If _c_o_l_o_r is specified as an empty string then no out- |
line is drawn for the arc. |
-start _d_e_g_r_e_e_s ||
Specifies the beginning of the angular range occupied |
by the arc. _D_e_g_r_e_e_s is given in units of degrees meas- |
ured counter-clockwise from the 3-o'clock position; it |
may be either positive or negative. |
-stipple _b_i_t_m_a_p ||
Indicates that the arc should be filled in a stipple |
pattern; _b_i_t_m_a_p specifies the stipple pattern to use, |
in any of the forms accepted by Tk_GetBitmap. If the |
-fill option hasn't been specified then this option has |
no effect. If _b_i_t_m_a_p is an empty string (the default), |
then filling is done in a solid fashion. |
-style _t_y_p_e ||
Specifies how to draw the arc. If _t_y_p_e is pieslice |
(the default) then the arc's region is defined by a |
section of the oval's perimeter plus two line segments, |
one between the center of the oval and each end of the |
perimeter section. If _t_y_p_e is chord then the arc's |
region is defined by a section of the oval's perimeter |
plus a single line segment connecting the two end |
points of the perimeter section. If _t_y_p_e is arc then |
the arc's region consists of a section of the perimeter |
alone. In this last case there is no outline for the |
arc and the -outline option is ignored. |
Tk 17
canvas(n) Tk Commands
-tags _t_a_g_L_i_s_t ||
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list. |
-width _o_u_t_l_i_n_e_W_i_d_t_h ||
Specifies the width of the outline to be drawn around |
the arc's region, in any of the forms described in the |
COORDINATES section above. If the -outline option has |
been specified as an empty string then this option has |
no effect. Wide outlines will be drawn centered on the |
edges of the arc's region. This option defaults to |
1.0. |
BITMAP ITEMS |
Items of type bitmap appear on the display as images with |
two colors, foreground and background. Bitmaps are created |
with widget commands of the following form: |
_p_a_t_h_N_a_m_e create bitmap _x _y ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?|
The arguments _x and _y specify the coordinates of a point |
used to position the bitmap on the display (see the -anchor |
option below for more information on how bitmaps are |
displayed). After the coordinates there may be any number |
of _o_p_t_i_o_n-_v_a_l_u_e pairs, each of which sets one of the confi- |
guration options for the item. These same _o_p_t_i_o_n-_v_a_l_u_e |
pairs may be used in itemconfigure widget commands to change |
the item's configuration. The following options are sup- |
ported for bitmaps: |
-anchor _a_n_c_h_o_r_P_o_s ||
_A_n_c_h_o_r_P_o_s tells how to position the bitmap relative to |
the positioning point for the item; it may have any of |
the forms accepted by Tk_GetAnchor. For example, if |
_a_n_c_h_o_r_P_o_s is center then the bitmap is centered on the |
point; if _a_n_c_h_o_r_P_o_s is n then the bitmap will be drawn |
so that its top center point is at the positioning |
point. This option defaults to center. |
-background _c_o_l_o_r ||
Specifies a color to use for each of the bitmap pixels |
whose value is 0. _C_o_l_o_r may have any of the forms |
accepted by Tk_GetColor. If this option isn't speci- |
fied, or if it is specified as an empty string, then |
the background color for the canvas is used. |
-bitmap _b_i_t_m_a_p ||
Specifies the bitmap to display in the item. _B_i_t_m_a_p |
may have any of the forms accepted by Tk_GetBitmap. |
Tk 18
canvas(n) Tk Commands
-foreground _c_o_l_o_r ||
Specifies a color to use for each of the bitmap pixels |
whose value is 1. _C_o_l_o_r may have any of the forms |
accepted by Tk_GetColor and defaults to black. |
-tags _t_a_g_L_i_s_t ||
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list.
LINE ITEMS
Items of type line appear on the display as one or more con-
nected line segments or curves. Lines are created with
widget commands of the following form:
_p_a_t_h_N_a_m_e create line _x_1 _y_1... _x_n _y_n ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?
The arguments _x_1 through _y_n give the coordinates for a
series of two or more points that describe a series of con-
nected line segments. After the coordinates there may be
any number of _o_p_t_i_o_n-_v_a_l_u_e pairs, each of which sets one of
the configuration options for the item. These same
_o_p_t_i_o_n-_v_a_l_u_e pairs may be used in itemconfigure widget com-
mands to change the item's configuration. The following
options are supported for lines:
-arrow _w_h_e_r_e
Indicates whether or not arrowheads are to be drawn at
one or both ends of the line. _W_h_e_r_e must have one of
the values none (for no arrowheads), first (for an
arrowhead at the first point of the line), last (for an
arrowhead at the last point of the line), or both (for
arrowheads at both ends). This option defaults to
none.
-arrowshape _s_h_a_p_e
This option indicates how to draw arrowheads. The
_s_h_a_p_e argument must be a list with three elements, each
specifying a distance in any of the forms described in
the COORDINATES section above. The first element of
the list gives the distance along the line from the
neck of the arrowhead to its tip. The second element
gives the distance along the line from the trailing
points of the arrowhead to the tip, and the third ele-
ment gives the distance from the outside edge of the
line to the trailing points. If this option isn't
specified then Tk picks a ``reasonable'' shape.
-capstyle _s_t_y_l_e
Specifies the ways in which caps are to be drawn at the
endpoints of the line. _S_t_y_l_e may have any of the forms
Tk 19
canvas(n) Tk Commands
accepted by Tk_GetCapStyle (butt, projecting, or
round). If this option isn't specified then it
defaults to butt. Where arrowheads are drawn the cap
style is ignored.
-fill _c_o_l_o_r
_C_o_l_o_r specifies a color to use for drawing the line; it
may have any of the forms acceptable to Tk_GetColor.
It may also be an empty string, in which case the line
will be transparent. This option defaults to black.
-joinstyle _s_t_y_l_e
Specifies the ways in which joints are to be drawn at
the vertices of the line. _S_t_y_l_e may have any of the
forms accepted by Tk_GetCapStyle (bevel, miter, or
round). If this option isn't specified then it
defaults to miter. If the line only contains two
points then this option is irrelevant.
-smooth _b_o_o_l_e_a_n
_B_o_o_l_e_a_n must have one of the forms accepted by |
Tk_GetBoolean. It indicates whether or not the line |
should be drawn as a curve. If so, the line is ren- |
dered as a set of Bezier splines: one spline is drawn |
for the first and second line segments, one for the |
second and third, and so on. Straight-line segments |
can be generated within a curve by duplicating the |
end-points of the desired line segment. |
-splinesteps _n_u_m_b_e_r ||
Specifies the degree of smoothness desired for curves: |
each spline will be approximated with _n_u_m_b_e_r line seg- |
ments. This option is ignored unless the -smooth |
option is true.
-stipple _b_i_t_m_a_p
Indicates that the line should be filled in a stipple
pattern; _b_i_t_m_a_p specifies the stipple pattern to use,
in any of the forms accepted by Tk_GetBitmap. If _b_i_t_-
_m_a_p is an empty string (the default), then filling is
done in a solid fashion.
-tags _t_a_g_L_i_s_t
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list.
-width _l_i_n_e_W_i_d_t_h
_L_i_n_e_W_i_d_t_h specifies the width of the line, in any of
the forms described in the COORDINATES section above.
Wide lines will be drawn centered on the path specified
Tk 20
canvas(n) Tk Commands
by the points. If this option isn't specified then it
defaults to 1.0.
OVAL ITEMS
Items of type oval appear as circular or oval regions on the
display. Each oval may have an outline, a fill, or both.
Ovals are created with widget commands of the following
form:
_p_a_t_h_N_a_m_e create oval _x_1 _y_1 _x_2 _y_2 ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?
The arguments _x_1, _y_1, _x_2, and _y_2 give the coordinates of two
diagonally opposite corners of a rectangular region enclos-
ing the oval. The oval will include the top and left edges
of the rectangle not the lower or right edges. If the
region is square then the resulting oval is circular; other-
wise it is elongated in shape. After the coordinates there
may be any number of _o_p_t_i_o_n-_v_a_l_u_e pairs, each of which sets
one of the configuration options for the item. These same
_o_p_t_i_o_n-_v_a_l_u_e pairs may be used in itemconfigure widget com-
mands to change the item's configuration. The following
options are supported for ovals:
-fill _c_o_l_o_r
Fill the area of the oval with _c_o_l_o_r. _C_o_l_o_r may have
any of the forms accepted by Tk_GetColor. If _c_o_l_o_r is
an empty string (the default), then then the oval will
not be filled.
-outline _c_o_l_o_r
_C_o_l_o_r specifies a color to use for drawing the oval's
outline; it may have any of the forms accepted by
Tk_GetColor. This option defaults to black. If _c_o_l_o_r
is an empty string then no outline will be drawn for
the oval.
-stipple _b_i_t_m_a_p
Indicates that the oval should be filled in a stipple
pattern; _b_i_t_m_a_p specifies the stipple pattern to use,
in any of the forms accepted by Tk_GetBitmap. If the
-fill option hasn't been specified then this option has
no effect. If _b_i_t_m_a_p is an empty string (the default),
then filling is done in a solid fashion.
-tags _t_a_g_L_i_s_t
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list.
-width _o_u_t_l_i_n_e_W_i_d_t_h
_o_u_t_l_i_n_e_W_i_d_t_h specifies the width of the outline to be
Tk 21
canvas(n) Tk Commands
drawn around the oval, in any of the forms described in
the COORDINATES section above. If the -outline option
hasn't been specified then this option has no effect. |
Wide outlines are drawn centered on the oval path |
defined by _x_1, _y_1, _x_2, and _y_2. This option defaults to
1.0.
POLYGON ITEMS
Items of type polygon appear as polygonal or curved filled
regions on the display. Polygons are created with widget
commands of the following form:
_p_a_t_h_N_a_m_e create polygon _x_1 _y_1 ... _x_n _y_n ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?
The arguments _x_1 through _y_n specify the coordinates for
three or more points that define a closed polygon. The
first and last points may be the same; whether they are or
not, Tk will draw the polygon as a closed polygon. After
the coordinates there may be any number of _o_p_t_i_o_n-_v_a_l_u_e
pairs, each of which sets one of the configuration options
for the item. These same _o_p_t_i_o_n-_v_a_l_u_e pairs may be used in
itemconfigure widget commands to change the item's confi-
guration. The following options are supported for polygons:
-fill _c_o_l_o_r
_C_o_l_o_r specifies a color to use for filling the area of
the polygon; it may have any of the forms acceptable to
Tk_GetColor. If _c_o_l_o_r is an empty string then the
polygon will be transparent. This option defaults to
black.
-smooth _b_o_o_l_e_a_n
_B_o_o_l_e_a_n must have one of the forms accepted by |
Tk_GetBoolean It indicates whether or not the polygon |
should be drawn with a curved perimeter. If so, the |
outline of the polygon becomes a set of Bezier splines, |
one spline for the first and second line segments, one |
for the second and third, and so on. Straight-line |
segments can be generated in a smoothed polygon by |
duplicating the end-points of the desired line segment. |
-splinesteps _n_u_m_b_e_r ||
Specifies the degree of smoothness desired for curves: |
each spline will be approximated with _n_u_m_b_e_r line seg- |
ments. This option is ignored unless the -smooth |
option is true.
-stipple _b_i_t_m_a_p
Indicates that the polygon should be filled in a stip-
ple pattern; _b_i_t_m_a_p specifies the stipple pattern to
use, in any of the forms accepted by Tk_GetBitmap. If
_b_i_t_m_a_p is an empty string (the default), then filling
Tk 22
canvas(n) Tk Commands
is done in a solid fashion.
-tags _t_a_g_L_i_s_t
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list.
RECTANGLE ITEMS
Items of type rectangle appear as rectangular regions on the
display. Each rectangle may have an outline, a fill, or
both. Rectangles are created with widget commands of the
following form:
_p_a_t_h_N_a_m_e create rectangle _x_1 _y_1 _x_2 _y_2 ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?
The arguments _x_1, _y_1, _x_2, and _y_2 give the coordinates of two
diagonally opposite corners of the rectangle (the rectangle
will include its upper and left edges but not its lower or
right edges). After the coordinates there may be any number
of _o_p_t_i_o_n-_v_a_l_u_e pairs, each of which sets one of the confi-
guration options for the item. These same _o_p_t_i_o_n-_v_a_l_u_e
pairs may be used in itemconfigure widget commands to change
the item's configuration. The following options are sup-
ported for rectangles:
-fill _c_o_l_o_r
Fill the area of the rectangle with _c_o_l_o_r, which may be
specified in any of the forms accepted by Tk_GetColor.
If _c_o_l_o_r is an empty string (the default), then then
the rectangle will not be filled.
-outline _c_o_l_o_r
Draw an outline around the edge of the rectangle in
_c_o_l_o_r. _C_o_l_o_r may have any of the forms accepted by
Tk_GetColor. This option defaults to black. If _c_o_l_o_r
is an empty string then no outline will be drawn for
the rectangle.
-stipple _b_i_t_m_a_p
Indicates that the rectangle should be filled in a
stipple pattern; _b_i_t_m_a_p specifies the stipple pattern
to use, in any of the forms accepted by Tk_GetBitmap.
If the -fill option hasn't been specified then this
option has no effect. If _b_i_t_m_a_p is an empty string
(the default), then filling is done in a solid fashion.
-tags _t_a_g_L_i_s_t
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list.
Tk 23
canvas(n) Tk Commands
-width _o_u_t_l_i_n_e_W_i_d_t_h
_O_u_t_l_i_n_e_W_i_d_t_h specifies the width of the outline to be
drawn around the rectangle, in any of the forms
described in the COORDINATES section above. If the
-outline option hasn't been specified then this option
has no effect. Wide outlines are drawn centered on the |
rectangular path defined by _x_1, _y_1, _x_2, and _y_2. This
option defaults to 1.0.
TEXT ITEMS
A text item displays a string of characters on the screen in
one or more lines. Text items support indexing and selec-
tion, along with the following text-related canvas widget
commands: dchars, focus, icursor, index, insert, select. |
Text items are created with widget commands of the following
form:
_p_a_t_h_N_a_m_e create text _x _y ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?
The arguments _x and _y specify the coordinates of a point
used to position the text on the display (see the options
below for more information on how text is displayed). After
the coordinates there may be any number of _o_p_t_i_o_n-_v_a_l_u_e
pairs, each of which sets one of the configuration options
for the item. These same _o_p_t_i_o_n-_v_a_l_u_e pairs may be used in
itemconfigure widget commands to change the item's confi-
guration. The following options are supported for text
items:
-anchor _a_n_c_h_o_r_P_o_s
_A_n_c_h_o_r_P_o_s tells how to position the text relative to
the positioning point for the text; it may have any of
the forms accepted by Tk_GetAnchor. For example, if
_a_n_c_h_o_r_P_o_s is center then the text is centered on the
point; if _a_n_c_h_o_r_P_o_s is n then the text will be drawn
such that the top center point of the rectangular
region occupied by the text will be at the positioning
point. This option defaults to center.
-fill _c_o_l_o_r
_C_o_l_o_r specifies a color to use for filling the text
characters; it may have any of the forms accepted by
Tk_GetColor. If this option isn't specified then it
defaults to black.
-font _f_o_n_t_N_a_m_e
Specifies the font to use for the text item. _F_o_n_t_N_a_m_e
may be any string acceptable to Tk_GetFontStruct. If
this option isn't specified, it defaults to a system-
dependent font.
-justify _h_o_w
Tk 24
canvas(n) Tk Commands
Specifies how to justify the text within its bounding
region. _H_o_w must be one of the values left, right, or
center. This option will only matter if the text is
displayed as multiple lines. If the option is omitted,
it defaults to left.
-stipple _b_i_t_m_a_p
Indicates that the text should be drawn in a stippled
pattern rather than solid; _b_i_t_m_a_p specifies the stipple
pattern to use, in any of the forms accepted by
Tk_GetBitmap. If _b_i_t_m_a_p is an empty string (the
default) then the text is drawn in a solid fashion.
-tags _t_a_g_L_i_s_t
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list.
-text _s_t_r_i_n_g
_S_t_r_i_n_g specifies the characters to be displayed in the
text item. Newline characters cause line breaks. The
characters in the item may also be changed with the
insert and delete widget commands. This option
defaults to an empty string.
-width _l_i_n_e_L_e_n_g_t_h
Specifies a maximum line length for the text, in any of
the forms described in the COORDINATES section abov.
If this option is zero (the default) the text is broken
into lines only at newline characters. However, if
this option is non-zero then any line that would be
longer than _l_i_n_e_L_e_n_g_t_h is broken just before a space
character to make the line shorter than _l_i_n_e_L_e_n_g_t_h;
the space character is treated as if it were a newline
character.
WINDOW ITEMS
Items of type window cause a particular window to be |
displayed at a given position on the canvas. Window items |
are created with widget commands of the following form: |
_p_a_t_h_N_a_m_e create window _x _y ?_o_p_t_i_o_n _v_a_l_u_e _o_p_t_i_o_n _v_a_l_u_e ...?|
The arguments _x and _y specify the coordinates of a point |
used to position the window on the display (see the -anchor |
option below for more information on how bitmaps are |
displayed). After the coordinates there may be any number |
of _o_p_t_i_o_n-_v_a_l_u_e pairs, each of which sets one of the confi- |
guration options for the item. These same _o_p_t_i_o_n-_v_a_l_u_e |
pairs may be used in itemconfigure widget commands to change |
the item's configuration. The following options are |
Tk 25
canvas(n) Tk Commands
supported for window items: |
-anchor _a_n_c_h_o_r_P_o_s ||
_A_n_c_h_o_r_P_o_s tells how to position the window relative to |
the positioning point for the item; it may have any of |
the forms accepted by Tk_GetAnchor. For example, if |
_a_n_c_h_o_r_P_o_s is center then the window is centered on the |
point; if _a_n_c_h_o_r_P_o_s is n then the window will be drawn |
so that its top center point is at the positioning |
point. This option defaults to center. |
-height _p_i_x_e_l_s ||
Specifies the height to assign to the item's window. |
_P_i_x_e_l_s may have any of the forms described in the COOR- |
DINATES section above. If this option isn't specified, |
or if it is specified as an empty string, then the win- |
dow is given whatever height it requests internally. |
-tags _t_a_g_L_i_s_t ||
Specifies a set of tags to apply to the item. _T_a_g_L_i_s_t |
consists of a list of tag names, which replace any |
existing tags for the item. _T_a_g_L_i_s_t may be an empty |
list. |
-width _p_i_x_e_l_s ||
Specifies the width to assign to the item's window. |
_P_i_x_e_l_s may have any of the forms described in the COOR- |
DINATES section above. If this option isn't specified, |
or if it is specified as an empty string, then the win- |
dow is given whatever width it requests internally. |
-window _p_a_t_h_N_a_m_e ||
Specifies the window to associate with this item. The |
window specified by _p_a_t_h_N_a_m_e must either be a child of |
the canvas widget or a child of some ancestor of the |
canvas widget. _P_a_t_h_N_a_m_e may not refer to a top-level |
window.
APPLICATION-DEFINED ITEM TYPES
It is possible for individual applications to define new
item types for canvas widgets using C code. The interfaces
for this mechanism are not presently documented, and it's
possible they may change, but you should be able to see how
they work by examining the code for some of the existing
item types.
BINDINGS
In the current implementation, new canvases are not given
any default behavior: you'll have to execute explicit Tcl
commands to give the canvas its behavior.
Tk 26
canvas(n) Tk Commands
CREDITS
Tk's canvas widget is a blatant ripoff of ideas from Joel
Bartlett's _e_z_d program. _E_z_d provides structured graphics in
a Scheme environment and preceded canvases by a year or two.
Its simple mechanisms for placing and animating graphical
objects inspired the functions of canvases.
KEYWORDS
canvas, widget
Tk 27
